EP 0 774 369 B1 discloses a twist-beam axle for motor vehicles, having two wheel-carrying longitudinal links and a transverse arm arranged therebetween. The longitudinal links are produced in a thixoforming process, i.e. in an (aluminum) die casting process with subsequent heat treatment. An insert made of a material of the same type as the material of the transverse arm, i.e. a weldable material, is inserted into the longitudinal link and joined with a form fit to the longitudinal link by means of the thixoforming process, such that it is possible to establish a welded join between the insert, i.e. effectively the longitudinal link, and the transverse arm. It is thus possible to produce a twist-beam axle in a hybrid construction, in which the longitudinal links are formed from aluminum and the transverse arm is formed from a solid steel material. This process has the disadvantage that the mutually corresponding components, i.e. the insert and the transverse arm, have to be strictly aligned with respect to one another for establishing the welding join. Such an alignment of the mutually corresponding components is very time-consuming and complex. This is also the case, in particular, because the insert is in fact exposed to considerable temperature influences and changes, such that it is displaced, even if minimally, from its original position. In addition, the wall thicknesses of the two components have to be matched to one another. The amount of work involved after the welded join has been established is also considerable, since the weld seam or the covering layer thereof itself should be worked to a smooth surface in order to avoid instances of notched loading. The quality of the weld seam root should also be checked. In addition, the weld seam subsequently has to be subjected to quality assurance so that it is possible to determine whether said weld seam has faults which reduce the service life, and this also has to be carried out using so-called nondestructive material tests such as surface cracking tests, X-rays and/or ultrasound investigations. In addition, the weld seam is arranged in a transition region between the transverse arm and the longitudinal links, which transition region is fundamentally subjected to particularly high torsional and bending loads.
EP 0 788 903 B1 likewise relates to a twist-beam rear axle in a hybrid construction. In EP 0 788 903 B1, too, the transverse arm is joined to the longitudinal link as the latter is being subjected to a die casting process, in that the aluminum shrinks during cooling. In this respect. EP 0 788 903 B1 identified that there is a risk of corrosion in the region in which the longitudinal link is joined to the transverse arm, and therefore special measures for treating the surface are provided.
In principle, it is therefore known to produce twist-beam axles, in particular twist-beam rear axles, in a hybrid construction, in which the longitudinal links are produced from a light metal, for example aluminum, and the transverse arm joining the two longitudinal links is produced from an iron metal, for example from a high-strength steel. This is based on the knowledge that vehicles having the smallest possible fuel consumption should be developed, the weight having a considerable influence on the fuel consumption. In this respect, it is expedient to use light metals, e.g. aluminum, or to replace steel components with aluminum components, and this noticeably leads to a reduction in weight and thus to fuel savings. However, a problem which is presented here is that light metals, e.g. aluminum, cannot be used unconditionally in regions which are subjected to high loads and undergo, for example, severe elastic deformation, and, e.g. in the case of the transverse arm joining the two longitudinal links, can also be referred to as the torsional profile. For reasons relating to strength and rigidity, high-strength steel is therefore provided in these regions. This is associated with the problem of a secure join between the two different types of materials. Here, a direct welded join is not possible, and this is why EP 0 774 369 B1 proposes the incorporation of steel inserts during the thixoforming process, although this leads to the aforementioned disadvantages.